1. Technical Field
The present invention relates to a method and apparatus for providing purified ice pieces and purified liquid water from a source of unpurified liquid water. More particularly, the present invention relates to a method and apparatus for producing and maintaining predetermined amounts of purified ice and purified liquid water in a common appliance housing.
2. Discussion of the Prior Art
In recent years there has been considerable public concern about the poor quality of tap water. Excessive chlorination, contamination by pesticides, and a variety of other factors have contributed to this concern. As a consequence, sales of bottled water and faucet filters have increased dramatically. Over the long run both of these solutions are expensive. It is desirable, therefore, to provide a low cost alternative to providing purified drinking water for the home and workplace. An attempt to provide purified water for household use by means of a freezing technique is disclosed in U.S. Pat. No. 3,338,065 (Ashley). In that patent there is a disclosure of an elongated freezing element disposed at the bottom of a tank of unpurified water. Water adjacent the surface of the freezing element freezes on that surface and accumulates as an ice mass until the freezing element is defrosted. The ice mass is released from the defrosted freezer element and floats to the top of the tank where it melts. Without stating how, the patent presumes that the formed ice mass is free of impurities present in the unpurified water; however, experience dictates that this modified static freezing approach does not significantly eliminate entrapment of impurities in the formed ice mass. The Ashley patent also states that the released ice mass is "washed" by the body of water as the mass floats upwardly in the tank toward the surface; however, this "washing" action, at best, removes impurities only from the surface and does not remove impurities trapped in the ice mass. The liquid at the top of the tank, where the ice masses melt, is described in the patent as being purified and, since it is less dense than the unpurified water in the tank, remains at the top of the tank without significantly mixing with the unpurified water. Water from the top of the tank may then be withdrawn for consumption. To the extent that this process purifies water, it is believed that the purification is minimal.
Similarly, the sale of purified ice cubes has increased significantly because of concern over impurities in ice cubes formed from unpurified tap water. Typically, when ice is made from tap water, the water is poured from the tap into compartments of trays where the water remains stationary as it freezes. This static process of freezing tap water whole, or in bulk, results in all of the original tap water impurities, including dissolved gases, remaining trapped in the ice cubes. In other words, the impurities are not chemically dissolved in the frozen water; rather, they are mechanically trapped in the resulting solidified ice cube structure. The resulting cubes are cloudy, as opposed to the clear appearance of purified ice, and are porous such that they tend to absorb odors from the refrigerator and freezer. Even if those commercial refrigerator-freezers that have a built-in automatic icemaking feature, the original water source is tap water, and the tap water is frozen in bulk. Consequently, the resulting ice cubes contain the trapped tap water impurities and are also porous in texture.
It is known in the prior art that unpurified liquid water may be issued forcibly against a surface that is cold enough to cause progressive accumulation of a mass of ice thereon. The stream of water, flowing over the growing ice mass, washes away impurities in the water before the impurities can be trapped in the ice mass. Systems using this flowing or dynamic freezing technique are disclosed in U.S. Pat. Nos. 2,341,721 (Whitney), and 3,170,779 (Karnofsky). Generally, these systems are directed to large scale freezing and purifying operations that are not suitable for producing relatively small ice pieces (i.e., pieces the size of ice cubes as used in drinks). If the known dynamic freezing process were employed in a household refrigerator, therefore, it would be necessary to break the resulting ice mass into small pieces suitable for use in drinks; the prior art does not address the problem. Further, the dynamic freezing technique has generally required an ice making machine made specifically for that purpose and not as an adaption to a household refrigerator. A separate icemaking machine using the dynamic freezing process would be expensive and not practical for most consumer applications.